Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
  • B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B15/00—Other accessories for centrifuges
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B7/00—Elements of centrifuges
  • B04B7/02—Casings; Lids
  • B04B7/04—Casings facilitating discharge
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
  • B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
  • B04B2001/2041—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl with baffles, plates, vanes or discs attached to the conveying screw
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
  • B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
  • B04B2001/2075—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl with means for recovering the energy of the outflowing liquid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
  • B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
  • B04B2001/2083—Configuration of liquid outlets

Definitions

• the invention relates to a decanter centrifuge with a rotating bowl provided with at least one solids discharge port and at least one clarified liquid discharge port and a screw conveyor disposed coaxially within said rotating bowl so as to be included in said rotating bowl rotated in the same direction with a differential rotational speed, where a feed suspension to be separated is introduced into a ring shaped space formed between said rotating bowl and said screw conveyor through a central feed pipe fixed to the end of the screw conveyor and supported in at least one bearing and can be separated by centrifugal force into a solid and a liquid phase so that said solid phase is discharged from said solid discharge port and said liquid phase is discharged from said clarified liquid discharging apparatus.
• a decanter centrifuge in the state of the art is shown in EP 0 447 742 A2 where the solid discharge port is arranged at the inside of the feed pipe end bearing.
• the liquid discharge port for the clarified liquid is on the side of the end plate connected to the drive shaft of the bowl and is equipped with a weir, which can be adjusted in its height by an adjusting weir board.
• the drive shaft has to have a certain diameter, usually in the range of the screw shaft, the liquid outlet can only be a great distance away from the axis. This leads to high energy consumption.
• the goal of the invention is thus a reduction of power loss from accelerated liquids and solids by reducing the discharge radius to an absolute minimum.
• a further embodiment of the invention is characterized by the sealing at the end of the feed pipe being provided as a double axial sealing. So it can be managed that one seal seals between the rotary feed pipe and the stationary supply pipe for the feed suspension and another seal seals between the headwall shaft of the rotor and the stationary part of the decanter centrifuge. This means that it will be possible to use the pressure from the feed pump to support the cake transport in the solids transporting part of the bowl, thereby eliminating the need for variable speed conveyor control and equipment.
• Another embodiment of the invention is characterized by a liquid phase outlet for the clarified liquid being arranged between the bearing and the sealing.
• the liquid phase valve being adjustable, where the liquid phase valve can be adjusted during operation of the decanter centrifuge and/or the liquid phase valve can be adjusted by a motor.
• a further advantageous embodiment of the invention is characterized by a channel for lubrication water being provided between the two seals and a bearing at the end of the rotating screw, which is arranged concentrically between the shaft of the rotating bowl and the shaft of the rotating screw.
• liquid phase conduit being arranged in the shaft of the rotating bowl. So it is incorporated in the main part and no separate part.
• FIG. 1 illustrates a decanter centrifuge according to the present invention
• Fig. 2 shows the feed end of the decanter centrifuge with the liquid phase valve
• Fig. 3 shows an alternative arrangement for a three-phase application.
• FIG. 1 a decanter centrifuge according to the invention, which has the following structure.
• a rotating bowl 1 is a combination of a conical section and a cylindrical section.
• a bowl-head 3 is fixed at the larger radius side of the rotating bowl 1 so as to close the rotating bowl 1.
• the hollow shaft 8 of the bowl-head 3 is extended from the bowl-head 3 so as to communicate with the hollow of the rotating bowl 1.
• the hollow shaft 9 is extended from the back end of the bowl 1, so as to communicating with the hollow of the rotating bowl 1.
• the hollow shaft 8 of the bowl-head 3 and the hollow shaft 9 of the bowl 1 are pivoted in bearings 18 and 19 respectively. Accordingly, the rotating bowl 1 can be supported horizontally and rotated with a high speed by a rotational force, which is transmitted by rotating driving means (not shown).
• a screw conveyor 2 is provided in the hollow portion of the rotating bowl 1.
• the screw conveyor 2 is pivoted coaxially with the rotating horizontal axis of the bowl 1 by means of bearings 16 and 17.
• a hollow tube 12 of the screw conveyor 2 is provided coaxially at the centre of the rotating bowl 1.
• a screw blade 13 extends helically the full length of the hollow tube 12 so as to almost reach the inner surface of the bowl 1.
• a transforming shaft 20 is provided in the hollow shaft 9 of the back end . Its one end is connected to the end part of the hollow tube 12 of the screw conveyor 2 and its other end is connected to conveyor drive 22.
• the bowl 1 with the screw conveyor 2 can be rotated with the high rotational speed.
• the rotating bowl 1 and the screw conveyor 2 are rotated in the same direction, while there is a slightly differential speed between them. This may be either accomplished by a gear unit or by different types of conveyor drives.
• a solid discharge port 11 is formed at the smaller radius side of the rotating bowl 1 so that solidified particles scraped together can be discharged from the solids discharge port 11.
• Fig. 2 shows the end part of the decanter centrifuge at the side of the bowl-head 3.
• the bowl- head 3 is fixed to the rotating bowl 1.
• the rotating speed may be approx 4000 rpm as an example.
• Inside is the rotating screw conveyor 2 with the hollow tube 12 and the thereon fixed blades 13.
• the screw conveyor 2 rotates in the same direction as the bowl 1. In case it is faster it may run at a speed of approx 4012 rpm, which is slightly different to the rotational speed of the rotating bowl 1.
• the screw conveyor 2 is pivoted coaxially with the rotating horizontal axis of the bowl 1 by means of bearing 16.
• Bowl-head 3 is extended by a hollow shaft 8 which is supported by a bearing stand 18.
• Feed pipe 10 is protruding inside the hollow shaft 8 of the rotating bowl 1 from the hollow tube 12 of screw conveyor 2 and is rotating with the screw conveyor.
• the feed suspension to be separated is supplied from feed pipe 10, while the rotating bowl 1 and the screw conveyor 2 are rotating with each high rotational speed, the feed suspension is introduced to the external side of the hollow tube 12 through feed ports 24 as known in the state of the art. So the introduced feed suspension is continuously splashed towards the peripheral inner surface of the rotating bowl 1 by a centrifugal force caused by the rotation of the rotating bowl 1. Therefore a ring shaped pool is formed along the peripheral internal face of the rotating bowl 1.
• the solid particles of higher density than the liquid of the feed suspension are separated from the clarified liquid to be precipitated by the high g-force created by the rotational speed on the bottom of the pool. These particles are scraped towards the conical end of the bowl 1 of Fig. 1 by means of the screw blades 13 and discharged from the solids discharge port 11.
• the clarified liquid which collects on the outer surface of the hollow tube 12, flows to a channel 15 and enters a liquid phase conduit 4, which is formed in the shaft 8.
• This liquid phase conduit 4 extends trough the bowl-head 3 and the bearing stand 18 and opens into liquid phase outlet 5. While the liquid phase conduit 4 is rotating with the bowl 1, the liquid phase outlet 5 is stationary.
• the amount of liquid phase (clarified liquid) can be controlled with a liquid phase discharge valve 14.
• This liquid phase discharge valve 14 may be varied by a hand wheel 23 via a transmission or alternatively by a motor. By varying the liquid phase discharge valve 14 it will be possible to use the pressure from the feed pump (not shown) to support the cake transport in the solids transporting part of the bowl 1, thereby eliminating the need for variable speed conveyor control and equipment.
• the feed pump not shown
• the level of liquid inside the bowl will be constant and defined by the discharge port 11 having the largest radius from the rotational centre.
• a baffle disc 21 arranged on the conveyor will form a barrier between a separation part and a solids transport part of the bowl cavity, only leaving a small gap between the bowl wall and the baffle periphery.
• this gap becomes a filled with solids of a high viscosity, thereby forming a plug that causes the liquid level in the separation part of the bowl to become closer to the rotational centre, until it reaches the liquid discharge radius (which is smaller than the solids discharge radius).
• the pressure on the separation side of the baffle will become larger than the pressure on the transport side of the baffle and this pressure difference thereby aid the transport of solids through the gap and "up" to the solids discharge level.
• the pressure from the feed pump will add to the pressure in the cavity if the level inside the cavity comes closer to the rotational axis than the liquid discharge radius.
• the liquid phase discharge valve 14 will, when becoming partly closed, increase the pressure loss across the liquid discharge port and thereby increase the liquid discharge level, until it becomes coincident with the axis, and the bowl cavity is filled.
• the pressure from the feed pump directly adds to the pressure at the baffle gap created by the centrifugal force, and the solids flow through the gap can therefore be controlled by regulation of the liquid phase valve gap.
• the solids transport can be controlled by the liquid phase discharge valve 14 as explained above, the dependency of the solids dryness of the conveyor speed is becoming less, and it will be possible to remove the control system for the conveyor speed and only have a fixed speed defined by the conveyor transmission ratio.
• Fig. 3 an embodiment of the invention is shown which is useful when three phases exist. It operates similar to the embodiment of figures 1 and 2, so that the solids are discharged on the end of the small radius of the rotating bowl 1 (not shown here) and the liquid phase may be separated into a light phase and a heavy phase. While the light phase follows the way already described earlier through liquid phase conduit 4 into liquid phase outlet 5, an additional
• conical ring weir 26 which separates the light phase and the heavy phase.
• the heavy phase then passes through an opening 27 which is covered by a ring shaped weir 28, to adjust the height of the opening and thus gives a possibility of adjusting the properties of the phases.

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• Centrifugal Separators (AREA)

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• 2014
  • 2014-03-14 EP EP14000941.6A patent/EP2918345B1/en active Active
  • 2014-03-14 ES ES14000941T patent/ES2774429T3/es active Active
  • 2014-03-14 DK DK14000941.6T patent/DK2918345T3/da active
• 2015
  • 2015-03-05 WO PCT/EP2015/054586 patent/WO2015135823A1/en active Application Filing
  • 2015-03-05 CA CA2942707A patent/CA2942707C/en active Active
  • 2015-03-05 US US15/125,638 patent/US10058876B2/en active Active
  • 2015-03-05 BR BR112016018597-8A patent/BR112016018597B1/pt active IP Right Grant
  • 2015-03-05 RU RU2016138660A patent/RU2676983C2/ru active
  • 2015-03-05 AU AU2015230227A patent/AU2015230227B2/en not_active Ceased
  • 2015-03-05 JP JP2016555293A patent/JP6718821B2/ja active Active
  • 2015-03-05 SG SG11201606315YA patent/SG11201606315YA/en unknown
  • 2015-03-05 KR KR1020167028703A patent/KR102399026B1/ko active IP Right Grant
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